CN108598655B

CN108598655B - Compact broadband rectangular waveguide coupler

Info

Publication number: CN108598655B
Application number: CN201810441104.4A
Authority: CN
Inventors: 徐勇; 孙淼; 彭廷会; 李洋; 王兆栋; 罗勇
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2018-05-10
Filing date: 2018-05-10
Publication date: 2020-05-12
Anticipated expiration: 2038-05-10
Also published as: CN108598655A

Abstract

The invention discloses a compact broadband rectangular waveguide coupler, relates to the technical field of microwave and millimeter wave devices, and particularly relates to a compact broadband rectangular waveguide coupler. In order to widen the working bandwidth of the rectangular waveguide and improve the coupling flatness of the coupler, the invention provides a compact broadband rectangular waveguide coupler; different from the traditional waveguide coupler, the rectangular waveguide coupler adopts the coupling array consisting of the square holes and the narrow slits, so that the structure of the coupler is compact and the coupler is easy to process, and the coupling fluctuation realized in the working frequency band (26.5GHz-40GHz) is lower than 0.3 dB. The coupling hole array formed by the small square holes and the narrow slits is simple in structure, and the coupler is compact in overall structure and easy to process.

Description

Compact broadband rectangular waveguide coupler

Technical Field

The invention relates to the technical field of microwave and millimeter wave devices, in particular to a compact broadband rectangular waveguide coupler.

Background

The rectangular waveguide coupler has wide application space in the fields of microwave wireless communication systems, microwave on-line measurement, radar reflection monitoring, broadband high-power attenuation and the like. The microwave energy sampling device has the main functions of accurately sampling energy transmitted in a microwave system and extracting a part of microwave energy so as to carry out time domain envelope monitoring, power measurement, spectrum measurement and the like on the energy transmitted in the microwave system through measuring instruments such as an oscilloscope, a miniwatt meter, a frequency spectrograph and the like. With the continuous development of microwave technology, the demand for waveguide couplers is also changing and increasing. In order to meet different requirements of electronic equipment development, the rectangular waveguide coupler is also developed from single-hole coupling to multi-hole coupling and from narrow-edge coupling to wide-edge coupling of the waveguide so as to meet different requirements of broadband, weak coupling and strong coupling. The traditional waveguide coupler with single-hole coupling has the advantages of simple structure, fewer parameters and more convenient design and processing, but the working bandwidth is too narrow to be suitable for broadband application of microwave frequency bands. Then, in order to widen the operating frequency range of the aperture coupling device, an aperture coupling array must be used, and the distribution form of the coupling array commonly used mainly includes: equidistant pore size distribution, binomial distribution, chebyshev distribution, and the like. Although the porous array waveguide coupler obviously improves the working bandwidth, the problems of longer waveguide coupler length, overlarge volume, high processing precision, higher insertion loss and the like are brought. Therefore, the traditional rectangular waveguide coupling has difficulty in combining compactness in size, high coupling flatness and certain broadband.

In order to realize that the rectangular waveguide coupler has a compact structure and a wider working bandwidth, the porous rectangular waveguide coupler with staggered coupling holes (patent number CN201210282690.5, inventor's royal flush) designs a structure that coupling holes are staggered on the H surface of a rectangular waveguide to realize the coupling of microwave energy, and the structure is simple and compact, but a higher coupling flatness cannot be obtained. A porous rectangular waveguide coupler (patent number CN201610312777.0, inventor Wangzhigang, etc.) has proposed that two rows of symmetrical coupling holes are symmetrically loaded on the wide side of the waveguide, each row has three coupling holes, the middle part is a square hole, and the two sides are triangular holes.

The traditional rectangular waveguide coupler mostly adopts a porous coupling mode in order to obtain a wider working bandwidth, and meanwhile, the coupling flatness is improved by increasing the number of coupling holes, but the size of the traditional directional coupler is larger, the processing precision requirement is high, and the insertion loss is high. Based on the background and the requirement, the invention designs the rectangular waveguide coupler with compact structure and flat coupling degree.

Disclosure of Invention

In order to widen the working bandwidth of the rectangular waveguide and improve the coupling flatness of the coupler, the invention provides a compact broadband rectangular waveguide coupler; different from the traditional waveguide coupler, the rectangular waveguide coupler adopts the coupling array consisting of the square holes and the narrow slits, so that the structure of the coupler is compact and the coupler is easy to process, and the coupling fluctuation realized in the working frequency band (26.5GHz-40GHz) is lower than 0.3 dB.

The invention adopts the following technical scheme: a compact broadband rectangular waveguide coupler, the coupler comprising: the waveguide comprises a main waveguide, an auxiliary waveguide, a coupling channel, a wave-absorbing material, a curved waveguide and an output waveguide; the main waveguide and the auxiliary waveguide are identical rectangular waveguides, and H surfaces are parallel to each other; the coupling channel is arranged between the main waveguide and the auxiliary waveguide; the output waveguide is communicated with one end of the auxiliary waveguide through the bent waveguide, and a wave-absorbing material is arranged inside the other end of the auxiliary waveguide; the coupling channel comprises 4 square channels arranged in an array and two coupling gaps connected with the square channels, and the coupling gaps are perpendicular to the propagation direction of the inner wave of the main waveguide or the auxiliary waveguide.

Further, the length of the transmission cavity of the main waveguide and the transmission cavity of the auxiliary waveguide are 7.12mm, and the width of the transmission cavity of the main waveguide and the transmission cavity of the auxiliary waveguide are 3.56 mm.

Furthermore, the wave-absorbing material is filled in a tangent angle of the secondary waveguide, the tangent angle is triangular prism-shaped, the intersection point of the tangent angle on the long side of the secondary waveguide transmission cavity is the middle point of the long side, and two right-angle sides of a bottom right-angled triangle of the triangular prism-shaped are respectively 3.56mm and 8 mm. The structure enlarges the contact area between the structure and the microwave signal for absorbing the microwave signal which propagates reversely, and the material of the structure is silicon carbide.

Further, the bending angle of the curved waveguide is 90 °. The function of the device is to change the propagation direction of energy in the secondary waveguide, and facilitate the connection with an external detection system.

Furthermore, the side length of the square channel in the coupling channel is 0.8mm by 0.8mm, the length of the coupling gap is 4mm, the width of the coupling gap is 0.12mm, and the distance between the main waveguide and the auxiliary waveguide is 1.5 mm.

The coupling hole array (3) of the compact broadband rectangular waveguide coupler is composed of 4 square holes which are symmetrically loaded in two rows and two columns on the common and common plane of the main waveguide and the auxiliary waveguide and a narrow slit loaded between the two rows of square holes. The distance from the square hole to the central line of the waveguide influences the coupling smoothness of the coupler, the specific value of the coupling smoothness is obtained by optimizing simulation software, the size and the height of the square hole and the width of the narrow slit influence the coupling degree of the coupler, and the value of the coupling smoothness is determined by the coupling degree of the coupler; the distance of each row of square holes is about a quarter wavelength, which satisfies the phase superposition principle.

The invention has the beneficial effects that:

(1) the coupling hole array formed by the small square holes and the narrow slits is simple in structure, and the coupler is compact in overall structure and easy to process.

(2) In the similar products, the compact broadband rectangular waveguide coupler has wider working frequency band and stable coupling degree, the coupling waveguide is lower than 0.3dB in the working frequency band of 26.5-40GHz, and simultaneously, the compact broadband rectangular waveguide coupler has larger power capacity.

Drawings

FIG. 1 is a schematic diagram of a compact broadband rectangular waveguide coupler

FIG. 2 is a side view of a compact broadband rectangular waveguide coupler

FIG. 3 is a top view of a compact broadband rectangular waveguide coupler

FIG. 4 coupling degree obtained by simulation of compact broadband rectangular waveguide coupler

FIG. 5 reflection coefficient of transmission port of compact broadband rectangular waveguide coupler

Detailed Description

The invention will be explained in further detail below with reference to an example of a design of a rectangular waveguide coupler operating in the Ka-band (26.5GHz-40GHz) and the accompanying drawings:

input signal mode: rectangular waveguide TE10 mode;

working frequency band: ka band (26.5GHz-40 GHz);

FIG. 1 is a schematic diagram of a compact broadband rectangular waveguide coupler; FIG. 2 is a side view of a compact broadband rectangular waveguide coupler; fig. 3 is a top view of a compact broadband rectangular waveguide coupler. The invention is novel and comprises: the wave absorbing material comprises a main waveguide 1, an auxiliary waveguide 2, a coupling hole array 3 consisting of square small holes and narrow slits, a wave absorbing material 4 and a bent waveguide 5. Wherein:

main waveguide 1 and sub-waveguide 2: the main waveguide and the auxiliary waveguide are Ka waveband standard rectangular waveguides BJ320, and a is 7.12mm and 3.56 mm;

coupling hole array 3 composed of square small holes and narrow slits: the side length of the square hole is 0.8 mm/0.8 mm, the length of the narrow slit is 4mm, the width is 0.12mm, and the height is 1.5 mm;

wave-absorbing material 4: the wave-absorbing material is in an oblique splitting shape and is loaded in the rectangular waveguide;

the curved waveguide 5: the radius of the curved waveguide is 5 mm.

Fig. 4 shows the coupling degree simulated by the compact broadband rectangular waveguide coupler. As can be seen from the figure, the coupling degree of the compact broadband rectangular waveguide coupler is 29.8-30.1dB in the working bandwidth of 26.5GHz-40GHz, and the fluctuation of the coupling degree in the bandwidth of 13.5GHz is within 0.3dB, which shows the excellent performance and wider working bandwidth of the coupler. Fig. 5 shows the reflection coefficients of the transmission ports of the compact broadband rectangular waveguide coupler, and it can be seen that the reflection of the ports is all greater than 35dB, and the reflection of the ports is small. The rectangular waveguide coupler has the advantages of excellent performance, wide working bandwidth, simple and compact structure and high application and popularization values.

The above examples are only for convenience of illustrating the present invention, and the compact broadband rectangular waveguide coupler provided by the present invention can also be applied to other frequency bands, and the specific size is determined by the corresponding frequency band and the operating mode.

Claims

1. A compact broadband rectangular waveguide coupler, the coupler comprising: the waveguide comprises a main waveguide, an auxiliary waveguide, a coupling channel, a wave-absorbing material, a curved waveguide and an output waveguide; the main waveguide and the auxiliary waveguide are identical rectangular waveguides, and H surfaces are parallel to each other; the coupling channel is arranged between the main waveguide and the auxiliary waveguide; the output waveguide is communicated with one end of the auxiliary waveguide through the bent waveguide, and a wave-absorbing material is arranged inside the other end of the auxiliary waveguide; the coupling channel comprises 4 square channels arranged in an array and two coupling gaps connected with the square channels, the coupling gaps are perpendicular to the propagation direction of the wave in the main waveguide or the secondary waveguide, the distance between every two rows of square channels is one quarter of wavelength, and the phase superposition principle is met.

2. A compact broadband rectangular waveguide coupler according to claim 1, wherein the sides of the square channels in the coupling channels are 0.8mm by 0.8mm, the coupling slot is 4mm long and 0.12mm wide, and the distance between the main waveguide and the sub-waveguide is 1.5 mm.

3. A compact broadband rectangular waveguide coupler according to claim 1 or 2, characterized in that the wave-absorbing material fills a corner cut of the secondary waveguide, the corner cut is a triangular prism, the intersection point of the corner cut at the long side of the secondary waveguide transmission cavity is the middle point of the long side, and the two right-angled sides of the bottom right-angled triangle of the triangular prism are 3.56mm and 8mm respectively.

4. A compact broadband rectangular waveguide coupler according to claim 1 or 2, characterized in that the bending angle of the curved waveguide is 90 °.

5. A compact broadband rectangular waveguide coupler according to claim 1 or 2, characterized in that the length of the transmission cavity of the primary waveguide and the secondary waveguide is 7.12mm and the width thereof is 3.56 mm.